Beyond rasters: introducing the new OGC web coverage service 2.0

Abstract

In the classical triad of vector, raster, and meta data, it is the raster part which is not yet sufficiently supported in SDIs nowadays. Consequently, integration of earth observation imagery, LIDAR, legacy map scans, etc. into Spatial Data Infrastructures (SDIs) remains incomplete. In terms of standards, the OGC Web Coverage Service (WCS) Standard defines open interfaces for accessing and processing of raster data, more generally: coverages. In August 2010, the completely overhauled WCS 2.0 has been adopted by OGC. To make coverages interchangeable across all OGC-based services, WCS 2.0 has been based on Geography Markup Language (GML) 3.2.1, with a small, backwards compatible addition to achieve informational completeness. In parallel to specification writing, its reference implementation and an online demo are being pursued. WCS 2.0 offers several advantages over previous versions, such as: support for general n-D raster data and non-raster coverage types; crisp, modular, and easy to understand; flexible and adaptive; harmonized with GML and Sensor Web Enablement (SWE); improved testability; and allows for efficient and scalable implementations. In this paper we present WCS 2.0 and some central design rationales. Further, we inspect the reference implementation architecture discussing some features critical for scalability. Finally, we give an outlook on next steps, such as the planned WCS Earth Observation Application Profile.